Baylissite is a rare hydrated potassium magnesium carbonate mineral that typically forms as delicate, colorless to white prismatic crystals. It is most frequently found in complex alkaline rock environments or rare evaporite deposits where specific geothermal conditions facilitate its growth.
Is this baylissite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch baylissite with a known reference. Baylissite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates.
Often confused with
Baylissite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside baylissite
Minerals reported to co-occur with baylissite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₂Mg(CO₃)₂·4H₂O
- Mohs hardness
- 2-3
- Density
- 2.06 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, radial aggregates
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in fractures in aplite granite and granodiorite
Where rockhounds find baylissite
Classic worldwide localities
- Gerstenegg-Sommerloch cable tunnel, north of the Grimsel Pass, Bern, Switzerland
Field-hunting tip
Where it forms: A secondary mineral in fractures in aplite granite and granodiorite. If you start seeing grimselite, schröckingerite, calcite in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify baylissite?+
Where is baylissite found?+
What rocks look like baylissite?+
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Find baylissite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
